Her former headteacher at Blackburn Central High School, Diane Atkinson, told the BBC: “She fled a war-torn zone as a refugee and came to the UK looking for a better life.

“She arrived with very little English and was soon inducted with BCHS, as we call ourselves, the family, and Blackburn.

“And she was a very, very intelligent young lady who very, very quickly picked up the command of English and worked incredibly hard to become the very, very best person she could be.”

Senior investigating officer Detective Superintendent Andy Cribbin, from Lancashire Constabulary’s Force Major Investigation Team (FMIT), said: “While we have now arrested a number of people as part of this investigation, our inquiries are very much ongoing and we continue to have a large team of officers and staff working around the clock to find out who was responsible for Aya’s death.

“Our thoughts are very much with Aya’s loved ones and her family are being supported by specially trained officers.

“I would like to thank those who have come forward to assist the investigation so far and I would continue to ask that anyone who has any information, however insignificant they may think it is, to get in touch.

“This is an absolutely tragic loss of a young life and we need to find out what happened – you may hold the key to help us do that so please don’t hesitate to contact us.

“We know a number of videos of the incident are on social media and it is important that, if people are aware of any footage, that they formally report this to us if they haven’t already done so as they are potential evidence.

“We would also ask people, even if they are well intentioned, not to share these videos out of respect for Aya and her family.

“Similarly, I would urge people not to speculate online about the cause of or motivation for the incident and to instead share what they know with us, as their information could prove vital.”